Abstract: UP8.00096 : The effects of sheared flow and parallel viscosity on the RWM stability boundaries*

Authors:

S.P. SmithS.C. Jardin(PPPL)

J.P. Freidberg(MIT)

L. Guazzotto(U. Rochester)

The complete spectrum of ideal MHD modes is computed for a
flowing circular cylindrical plasma surrounded by a resistive
wall. The formulation for the computation casts the MHD
stability problem in the standard form $\omega A x=B x$ by
coupling the resistive wall to the surface plasma perturbations
using a Green's function technique. In looking at the complete
spectrum, it is shown that the unstable resistive wall mode
(RWM) can be stabilized by uniform flow when i) The damped RWM
in the absence of flow resonates with the sound continuum and
ii) The Doppler shift associated with the flow is greater than
the damped mode's real frequency in the absence of flow. By
introducing flow shear, it is shown that the value of the flow
at the sound resonant surface is the parameter which most
determines stabilization (as opposed to the flow shear at the
sound resonant surface or the value of the flow at the edge of
the plasma.) Convergence studies demonstrate complete
stabilization in the limit of zero grid size even in the
absence of parallel viscosity. Introducing explicit parallel
viscosity reduces the resolution requirements for convergence,
but does not affect the region of stability.

*This work was partly performed under contract DE-AC05-06OR23100 between the US DOE and ORAU.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2009.DPP.UP8.96